运动前进食不同血糖指数食物对长跑能力的影响

目的 :探讨运动前进食不同血糖指数食物对长跑能力的影响。方法 :实验设计采用平衡重复测试法 ,8名男子耐力长跑运动员在间隔期不少于 7天内 ,在隔夜空腹情况下分别进食含相等热量的低血糖指数 [Glycemicindex (GI) ](GI =37)或高GI(GI =77)的碳水化合物 (CHO)食物 (CHO∶1 5g/kg体重 )。 2小时后 ,受试者在水平跑台上进行 2 1km的长跑能力测试。首 5km中 ,受试者以其 70 %VO2 max的速度跑步 ,而其后的 16km ,则可随意选择速度以最短时间完成。结果 :与高GI试验相比 ,所有受试者在进食低GI食物后的跑步时间明显缩短 (98 7± 2 0vs 10 1 5± 2 1min ,P<0 0 1)。整个跑步全程中 ,低GI试验的血糖及血清游离脂肪酸 (FFA)的水平较高GI试验为高。虽然进食高GI食物后两小时的血清胰岛素较高 ,但在运动过程中 ,血清胰岛素、皮质醇、血乳酸水平与低GI试验相比均无显著差异。与高GI试验相比 ,低GI试验中CHO氧化在能量供应上的依赖低 9 5 % ,而脂肪氧化则高 17 9%。结论 :在运动前 2小时进食低血糖指数的CHO食物 ,比提供同等热量的高血糖指数食物能更有效地提高长跑运动的能力。     

急性有氧运动对糖尿病大鼠肝脏和胰腺内质网应激蛋白和血糖的影响

目的:探讨急性有氧运动对糖尿病大鼠肝脏和胰腺内质网应激蛋白和血糖的影响,为糖尿病的运动疗法提供参考。方法:SPF级雄性SD大鼠55只,高脂饲料喂养配合腹腔注射小剂量链脲佐菌素制备2型糖尿病大鼠动物模型后,随机分为安静组(DM)和大、中、小三个强度有氧运动组(HIE-1、MIE-1、LIE-1),三个有氧运动组进行急性跑台运动,其运动速度分别为20 m/min、15 m/min和10 m/min,相当于70%VO2max、50%VO2max和30%VO2max负荷强度,持续运动1 h。运动后即刻检测空腹血糖(FBG)、糖化血清蛋白(GSP)、空腹胰岛素(Ins)、肝脏和胰腺的GRP78和caspase-12含量,并计算胰岛素抵抗指数(IRI)、胰岛素敏感指数(ISI)和β细胞功能指数(HBCI)。结果:各运动组糖尿病大鼠急性运动后血清空腹胰岛素较安静组均显著下降(P<0.01,P<0.01,P<0.05),胰岛素抵抗指数显著降低,胰岛素敏感指数显著升高,其中,大、中强度运动组变化有统计学意义(P<0.01)。中、小强度运动组肝脏和胰腺内质网应激蛋白GRP78和caspase-12较安静组均显著降低。结论:急性有氧耐力运动可降低糖尿病大鼠血糖水平,增强胰岛素敏感性,降低内质网过度应激状态,其机制可能与内质网应激蛋白参与调节有关。     

血糖负荷及其在健康和运动科学中的应用

餐后血糖水平除了与碳水化合物(CHO)的血糖指数(glycemic index,GI)高低有关外,还与食物中所含CHO的量(CHOamount)有密切关系。GI高的食物,如果CHO含量很少,尽管其容易转化为血糖,但其对血糖总体水平的影响并不大。因此GI值仅仅反映CHO的质量,并未反映出CHO的实际摄入含量。如果将摄入CHO的“质”和“量”结合起来,就产生了一个新的概念,即血糖负荷(glycemic load,GL)。近年来,GL在流行病学的预防和控制研究方面已成为热点。与食物中单纯的GI或者CHO的含量相比,GL在运动医学中的合理性、科学性以及应用前景更加广阔。本文从…     

补充巧克力对长时间中等度运动休闲跑步后恢复的影响

目的：研究运动前补充巧克力对运动引起的生理和代谢变化及恢复的影响。方法：１２名１８～２０岁男性休闲跑步自愿者作为受试实验对象,采用交叉设计,每名受试者参加两次试验,在跑步机上跑步１小时,运动中心率保持在１４８～１５０次／分。结果：运动前补充５６ｇ巧克力１５分钟后,血糖水平显著升高（５．４２±０．８３ｍｍｏｌ／Ｌ）并且在运动结束及其后的３０分钟仍保持在相当高的水平（４．９２±０．５７ｍｍｏｌ／Ｌ）,而补充安慰剂的对照组在运动后血糖水平低（３．９７±０．３７ｍｍｏｌ／Ｌ）,停止运动３０分钟后血糖低于正常水平（３．８４±０．３１ｍｍｏｌ／Ｌ）。血浆自由脂肪酸、血乳酸、血浆尿素氮水平以及自我感觉疲劳程度（ＲＰＥ）等结果均表明运动前补充巧克力提供运动和运动后恢复所必要的条件均有益。     

餐后不同运动因素对健康成人血糖和胰岛素的影响

目的:探讨餐后不同运动强度、持续时间、起始时间对健康成人血糖及胰岛素的影响.方法:7名年轻健康、不经常运动、BMI均低于20的受试者,参加有间歇的4组运动及前后2组静息实验,采用正交设计实验,运动因素为运动强度(3METs、5METs)、持续时间(15min、35min)、餐后运动起始时间(15min、30min),各因素分为两水平.检测空腹及服用标准餐后7个不同时间点(餐后15min、30min、45min、60min、90min、120min、150min)的血糖及胰岛素,计算血糖一时间曲线下面积(GAUC)和胰岛素一时间曲线下面积(IAUC),并监测运动能量消耗.结果:运动35分钟的餐后IAUC显著低于运动15分钟(P＜0.05);餐后起始运动时间为15分钟的GAUC及血糖峰值显著低于静息组(P＜0.05);不同运动强度间未见效果差异.持续35分钟运动的能量消耗显著高于持续15分钟;餐后15分钟开始运动的能量消耗显著高于30分钟,5METs强度运动的能量消耗显著高于3METs.结论:餐后持续运动35分钟较运动15分钟可显著改善餐后糖代谢;餐后15分钟开始运动产生的降低血糖峰值的效应优于餐后30分钟开始运动.     

模拟低氧耐受能力和高山运动能力之间的关系

我们对28名自愿受试者,年龄在20.3±0.7在海拔760米,Po2=147Torr进行了对外加负荷因素——模拟海拔7500米的耐受能力(Po2=58Torr)运动(PWC170试验)和吸入常氧高二氧化碳的研究。在海拔3,600米处(Po2为103Torr,天山),根据他们对模拟低氧的耐受程度,分别于在高原适应第3天和第20天测定了他们的运动能力.根据有效清醒时间的值将受试者分为3个组,第一组为低耐受组,有效清醒时间为8.0±1.2分钟,13例.第二组为中等耐受组为13.5±0.9分钟,8例,第三组为高耐受组为39.2±1.5分钟,7例.     

血糖指数及其在运动营养实践中的应用

血糖指数(Glycemic Index, 简称GI)的概念是由加拿大营养学家于1981年首次提出,它是指按进食碳水化合物(CHO)后2小时机体血糖反应的大小排列食物的一种方法[1].其最大特点是避免了个体间对CHO食物的绝对血糖反应产生较大差异的问题.一段时期以来,GI在糖尿病饮食疗法和肥胖控制的临床实践中发挥了举足轻重的作用[2,3].近年,GI的研究也逐步应用到运动营养领域中,为科学调配运动员训练比赛膳食提供了一个新思路.本文从血糖指数的概念、决定因素及血糖指数在运动营养实践中所作的研究进行小结,重点探讨运动前、中、后三种机体应激状态与相应的GI营养措施之间的关系,希望在运动饮食的选择上,对运动员、教练员及体育科研工作者有所启发.     

人体75%VO2max运动中骨骼肌丙酮酸脱氢酶系活性及丙酮酸含量变化

目的探讨75%最大吸氧量(VO2max)强度运动中人体骨骼肌丙酮酸含量和丙酮酸脱氢酶系(PDC)活性变化及其二者关系.方法健康男性大学生6人,受试者一条腿在功率自行车上做力竭运动120分钟,使肌糖原接近耗竭,作为糖原消耗腿.另一条腿作为糖原未消耗对照腿.两条腿分别以75% VO2max负荷(210±5W)在功率自行车上运动12分钟.运动前后取大腿股外侧肌活检标本,测定丙酮酸含量、PDC活性、糖原总量、6-磷酸葡萄糖、乳酸和三羧酸循环中间产物(TCAI)含量.结果显示,PDC活性与丙酮酸含量之间存在一定关系,75%VO2max运动后,肌糖原消耗肌肉中丙酮酸含量变化不明显,PDC活性也没有显著升高;而在肌糖原未消耗肌肉中,随着丙酮酸含量增加了1.7倍,PDC活性也升高了3.3倍.提示75%VO2max运动中丙酮酸可能是影响PDC活性的重要物质.     

75%VO_2max强度有氧运动对红细胞微观形态及流变学特性的影响

目的:通过重复性实验观察75 %VO2 max强度有氧运动对人体红细胞形态、粘度、聚集性和变形能力的影响。方法:正式实验前1周测定受试者的最大摄氧量。受试者间隔1周以75 %VO2 max强度完成1次蹬功率自行车运动1小时,每次运动前安静时和运动后即刻采静脉血测定全血粘度(高、中、低切)、血浆粘度(PV)、红细胞压积(Hct)、红细胞变形指数(TK)、聚集指数(RCA)和刚性指数(VR) ,扫描电镜(SEM)下观察红细胞微观形态变化。结果:3次实验均表明,75 %VO2 max强度运动可以使全血粘度各切变率、红细胞压积、变形指数、聚集指数和刚性指数显著增高;红细胞形态由双凹圆盘状变为单侧凹陷边缘肿胀的Ⅰ型口形红细胞或凹陷加深另一侧隆起似礼帽状的Ⅱ型口形红细胞。结论:1小时75 %VO2 max强度有氧运动后红细胞粘度、聚集性增大,压积升高,红细胞失去正常形态,变形能力下降,从而影响其正常的携带氧气和二氧化碳的功能。     

高强度划船运动对久坐青年男性餐后血糖、甘油三酯和胰岛素水平的影响

目的:探讨3分钟重复高强度间歇划船运动是否可以影响久坐青年男性高脂饮食后的血糖、甘油三酯和胰岛素的水平。方法:选择18名青年男性随机分为运动组和对照组。第1天,运动组进行17RPE的半小时间歇性高强度运动,对照组未做运动;第2天行75 g口服葡萄糖耐量试验(OGTT)并进食高脂食物,保持休息状态8个小时。间隔1周后两组对换,重复试验。期间采集静脉血监测空腹和餐后血糖、甘油三酯和胰岛素的变化,计算曲线下面积(AUC)和稳态模型评估的胰岛素抵抗指数(HOMA-IR)、β细胞功能指数(HOMA-β),评价胰岛素敏感性和胰岛β细胞功能。结果:在高脂饮食前14个小时进行高强度划船运动(运动能耗约为900 k J)可以显著降低空腹(P=0.004)和高脂餐后甘油三酯(P=0.005),而空腹和餐后的血糖及胰岛素水平没有显著变化(P>0.05)。结论:半小时间歇性高强度划船运动可以显著降低空腹和高脂餐后甘油三酯水平。     

Effect of CHO loading patterns on running performance

This study examined the influence of 3-day isoenergetic carbohydrate (CHO) loading with different glycemic index (GI) and glycemic load (GL) meals on running performance and metabolic responses. With a randomized crossover design, nine male runners performed a 1-h run at 70% VO2max followed by a 10-km performance run after a 3-day diet adaptation, which involved different GI and GL meals [CHO intake (%), GI, and GL per day were 73%, 80, and 553 for the high GI and high GL (HH); 73%, 36, and 249 for the low GI and low GL (LL); and 31%, 79, and 227 for the high GI and low GL (HL), respectively]. There were no differences in the time to complete the 10-km run between the two high-CHO trials; however, the performance in the LL trial was improved as compared to that in the HL trial (mean +/- SEM: HH vs. LL vs. HL: 51.3 +/- 5.3 vs. 48.6 +/- 1.3 vs. 55.3 +/- 6.9 min). It appears that the amount, rather than the nature, of the CHO consumed during the 3-day isoenergetic CHO loading may be the most overriding factor on subsequent metabolism and endurance run performance.     

Influence of high and low glycemic index meals on endurance running capacity

PURPOSE: The purpose of this study was to examine the effect of high and low glycemic index (GI) carbohydrate (CHO) pre-exercise meals on endurance running capacity. METHODS: Eight active subjects (five male and three female) ran on a treadmill at approximately 70% VO2max to exhaustion on two occasions separated by 7 d. Three hours before the run after an overnight fast, each subject was given in a single-blind, random order, isoenergetic meal of 850+/-21 kcal (mean+/-SEM; 67% carbohydrate, 30% protein, and 3% fat) containing either high (HGI) or low (LGI) GI carbohydrate foods providing 2.0 g CHO.kg(-1) body weight. RESULTS: Ingestion of the HGI meal resulted in a 580% and 330% greater incremental area under the 3-h blood glucose and serum insulin response curves, respectively. Performance times were not different between the HGI and LGI trials (113+/-4 min and 111+/-5 min, respectively). During the first 80 min of exercise in the LGI trial, CHO oxidation was 12% lower and fat oxidation was 118% higher than in the HGI trial. Although serum insulin concentrations did not differ between trials, blood glucose at 20 min into exercise in the HGI trial was lower than that during the LGI trial at the same time (3.6+/-0.3 mmol.L(-1) vs 4.3+/-0.3 mmol.L(-1); P < 0.05). During exercise, plasma glycerol and serum free fatty acid concentrations were lower in the HGI trial than in the LGI trial. CONCLUSIONS: This results demonstrate that although there is a relative shift in substrate utilization from CHO to fat when a low GI meal is ingested before exercise compared with that for a high GI meal, there is no difference in endurance running capacity.     

Effects of GI Meals on Intermittent Exercise

Pre-exercise meals or single foods containing low glycaemic index (LGI) carbohydrates (CHO) have been shown to enhance performance prior to prolonged steady state exercise compared to high glycaemic index (HGI) CHO. This study investigated the impact of HGI and LGI pre-exercise meals on intermittent high intensity exercise. Nine male recreational football players performed a football specific protocol followed by a 1 km time trial 3.5 h after ingesting 1 of 2 isoenergetic test meals (HGI: 870.3 kcal, LGI: 889.5 kcal), which were either HGI (GI: 80) or LGI (GI: 44). Blood glucose, fatty acids (FA), glycerol, β-hydroxybutyrate, lactate and insulin were assessed before, during, and after the exercise bout, whilst rates of CHO and fat oxidation were determined at 4 time points during the protocol. No significant differences were found for the 1 km time trial (LGI: 210.2±19.1 s: HGI: 215.8±22.6 s) (mean±SD), nor for any of the other variables measured (P>0.05) apart from a significant condition effect with FA and significant interaction effects observed for glucose, β-hydroxybutyrate and lactate (P<0.05). These findings suggest that the type of CHO ingested in a pre-match meal has no significant impact on performance or metabolic responses during 90 min of intermittent high intensity exercise.     

Resting and post‐exercise serum biomarkers of cardiac and skeletal muscle damage in adolescent runners

This study examined the response of serum biomarkers of cardiac and skeletal muscle damage at rest and after a routine workout of 21 km run in 12 male adolescent (16.2±0.6 years) long‐distance runners. Biomarkers of cardiac [troponins (cTnT, cTnI), creatine kinase MB mass (CK‐Mbmass)] and skeletal muscle [creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hydroxybutyrate dehydrogenase (HBD)] damage were assayed at rest, 2, 4 and 24 h post‐exercise. At rest, cTnT and cTnI were not detectable; however, CK, CK‐MBmass, AST, ALT and HBD were above corresponding clinical cut‐off values. Post‐exercise significant elevations above rest were observed for all biomarkers, except ALT, 2 and 4 h following the run, and remained elevated in cTnI, CK, CK‐MBmass, LDH and AST 24 h post‐workout. A significant increase in data points above clinical cut‐off values from rest to post‐exercise was reported for cTnT, cTnI and CK at 2 and 4 h, and in cTnI and CK 24 h post‐exercise. In conclusion, a 21 km run in adolescent runners increased post‐exercise biomarkers of cardiac and skeletal muscle damage.     

心血管疾病住院患者饮食生糖负荷和糖类、脂肪及蛋白质摄入量的研究

目的研究成年心血管疾病住院患者饮食生糖负荷情况及与代谢性疾病发病相关性,了解成年心血管疾病住院患者能量和糖类、脂肪及蛋白质生热营养素摄入情况。方法采用膳食回顾法估算118例成年心血管疾病住院患者的总能量及三大营养素的摄入量,根据食物血糖生成指数（glycemic index,GI）和糖类摄入量计算饮食生糖负荷（glycemic load,GL）。分析住院患者饮食GL的性别和年龄分布,分析不同饮食水平患者的膳食结构。结果成年心血管疾病住院患者每日膳食GL平均为256.7,老年患者平均为222.0,中、青年患者平均为278.6,中、青年患者高于老年患者。低膳食GL的患者膳食糖类供能比低,脂肪供能比高,谷薯类摄入低,脂肪摄入高,超重和肥胖发生率高。结论低膳食GL的患者粮谷类消费过低,脂肪消费过高,膳食结构不合理,以此作为患者的住院及家用饮食指导的依据,从而提供平衡、合理的膳食结构。     

Changes of polymorphonuclear granulocyte migration and lymphocyte proliferative responses in elite runners undergoing intense exercise

The immunoregulatory effects of intense exercise were examined measuring polymorphonuclear granulocyte (PMN) migration under agarose, lymphocyte proliferative responses after mitogen stimulation (phytohemagglutinin P, concanavalin A and pokeweed mitogen) and complement activation (C3 conversion) in the peripheral blood of elite runners undergoing maximal exertion. Eleven elite middle- and long-distance runners were tested in a 5-km race on a running track. PMN migration activity towards autologous serum and FMLP as chemoattractants both increased after intense physical activity. The lymphocytes showed increased proliferative responses to the mitogen stimulation 2 h after the run compared with pre-exercise values, and normalized activity after 24 h. The total number of lymphocytes in the peripheral blood markedly decreased 2 h after the run and the number of leukocytes increased. A tendency to a decrease in complement C3 conversion-was observed after the run, but within the estimated normal area. Our findings suggest that intense physical activity influences the cellular immune system.     

Effects of repeated endurance exercise on serum enzyme activities in well-conditioned males.

Daily fluctuations in serum enzyme activities during distance running in 3 well-conditioned males were measured for 8 consecutive days. During the study the exercise regimen comprised 8 mile runs on days 1, 2 and 5; a 10.5 mile run on day 3; a 15 mile run on day 4 and resting on days 6-8. Heart rate, rectal temperature, hematocrit, plasma hemoglobin, creatine phosphokinase (CPK, glutamic-oxaloacetic and glutamic-pyruvic transaminases, lactate dehydrogenase (LDH), adenylate kinase (AK), and lactate and pyruvate were measured before and after exercise and during the resting days. Significant increases occurred in heart rate and rectal temperature with each run but were unrelated to enzyme levels. Pre-exercise CPK levels, 49 plus or minus 1 mIU/ml on day 1, rose progressively to 123 plus or minus 25 mIU/ml on day 5, and returned to initial control levels by day 8. Post-exercise CPK levels were significantly greater than pre-exercise levels on each running day but were unrelated to the severity of the exercise. LDH and AK levels did not significantly change with the exercise stress, but pre-exercise AK levels in these trained males were higher than values in non-trained males (10-20 vs. 0-5 mIU/ml) (3). Post-exercise enzyme levels appeared unrelated to final heart rate, rectal temperature or plasma hemoglobin. These results suggest that (1) CPK, unlike the other enzymes studied, is a sensitive index of exercise stress in well-conditioned runners and (2) elevated CPK and AK levels in such runners represent physiologic responses. Appropriate caution should be used in making clinical judgements from these enzyme assays in trained individuals.     

Pre-exercise carbohydrate and fluid ingestion: influence of glycemic response on 10-km treadmill running performance in the heat

BACKGROUND: The purpose of this study was to determine the influence of ingesting solutions containing mixtures of carbohydrate (CHO) types on pre-exercise glycemic response, exercise-induced hypoglycemia, metabolic responses, and 10-km treadmill running performance in a warm environment. METHODS: Ten trained runners completed 6, self-paced 10-km treadmill runs one hour after ingesting 900 ml of one of the following test solutions: a water placebo (WP), an 8 g 100 ml-1 high fructose corn syrup solution (HFG; 72 g CHO), a 6 g 100 ml-1 glucose solution (GLU; 54 g CHO), a 6 g.100 ml-1 sucrose/glucose mixture (SUG; 54 g CHO), or banana with water to equal 900 ml (BAN; approx. 54 g CHO). The sixth condition was 675 ml of an 8 g.100 ml-1 HFCS solution (LFG; 54 g CHO). Blood samples were taken prior to ingestion and every 15 min during rest and at 15 and 30 min, and at the end of the 10-km run. Blood was analyzed for glucose (BG) insulin (IN), glycerol, lactate, and percent change in plasma volume. Urine volume during the 1 hour of rest and change in body mass during exercise were also determined. RESULTS: A significant (p < 0.05) correlation (r = -0.684) was seen between the pre-exercise glycemic response (PEGR = area under the resting BG curve) and the change in BG from pre-EX to 15 min of exercise. BG at 15 min of exercise was significantly higher in the WP (5.22 mM) versus the other conditions (HFG = 3.32, LFG = 3.91, GLU = 3.38, BAN = 3.74 & SUG = 3.63 mM). Pre-exercise IN was lower in the WP (6.54 U ml-1) condition versus the other conditions (HFG = 22.1, LFG = 16.2, GLU = 23.3, BAN = 18.8 & SUG = 12.8 U.ml-1). Ten km performance times were not different (WP = 41.87, HFG = 41.66, LFG = 41.79, GLU = 41.65, BAN = 41.53, and SUG = 41.75 min). A significantly greater body mass loss occurred due to urine production during the 60 min of rest in the WP compared to the other conditions. The degree of exercise-induced decline in blood glucose was related to the PEGR; however, the decline in BG did not affect 10-km running performance. In addition, there were no differences in the metabolic responses during exercise between the different CHO types, nor did the type of CHO influence running performance. Finally, the presence of CHO and/or electrolytes in the hydration solutions produced a better fluid retention during the 60-min pre-exercise rest period compared to water. CONCLUSIONS: The results confirmed that if a competitive athlete consumed a breakfast prior to ingesting a CHO-electrolyte beverage, a practice that is common, the glycemic responses may be different.     

低血糖指数膳食对肾移植术后早期糖代谢异常患者干预效应

目的探讨低血糖指数膳食对肾移植术后早期糖代谢异常患者干预效应。方法分析2009-01至2011-02100例肾移植术后早期患者糖代谢异常发生率,将糖代谢异常患者随机分为2组,每组27例,对照组自由膳食,干预组低血糖指数（glycemic index,GI）膳食,营养干预30 d,观察干预前后空腹血糖（fasting blood glucose,FPG）和餐后2 h血糖（2 h plasmaglucose,2 h PG）的变化情况。结果肾移植患者术后糖代谢异常发生率为54%,发生时间为术后15～180 d,前3个月发生率为44%。干预30 d后,干预组FPG和2 h PG恢复正常,与干预前比较差异有统计学意义（P〈0.01）,与对照组比较差异有统计学意义（P〈0.01）。结论低GI膳食可以积极控制肾移植术后早期患者糖代谢异常。